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Acrocarpus fraxinifolius Arn.

Protologue
Mag. Zool. Bot. 2: 547 (1838).
Family
Caesalpiniaceae (Leguminosae - Caesalpinioideae)
Chromosome number
2n = 24
Vernacular names
Pink cedar tree, Indian ash, shingle tree (En).
Origin and geographic distribution
Acrocarpus fraxinifolius orginates from tropical Asia, where it occurs naturally from Nepal and India to Thailand, southern China and western Indonesia. It is widely planted within and outside its natural area of distribution, e.g. in India, tropical America, but also in several countries in tropical Africa: Liberia, Nigeria, Rwanda, Burundi, Kenya, Uganda, Tanzania, Malawi, Zambia, Zimbabwe and Madagascar.
Uses
The wood is suitable for indoor construction, furniture, fence posts, beehives, boxes, packing cases, roof shingles, veneer and plywood. It is also used as firewood and for charcoal production. The wood is used to produce pulp for paper, but is rated as second-class for that purpose.
Acrocarpus fraxinifolius is widely planted as ornamental tree. The foliage is used as fodder, and the flowers are a source of nectar for honey bees. The tree has been recommended for reinforcing river banks and to stabilize terraces, and for use in agroforestry systems, although it has been reported to compete with crops. It produces good mulch. It is grown for shade in coffee and tea plantations, sometimes also in timber plantations and as windbreak.
Production and international trade
Although Acrocarpus fraxinifolius is planted in timber plantations, its wood is probably used on a local scale only.
Properties
The heartwood is pale pinkish, bright red to reddish brown with darker streaks, distinctly demarcated from the pale yellowish sapwood. The grain is straight to slightly interlocked, sometimes wavy, texture coarse and even. The wood is lustrous.
The wood is medium-weight with a density of 520–700 kg/m³ at 12% moisture content. It air dries well when not too rapidly dried; end splitting and checking may occur. The rates of shrinkage are moderate. In India boards 2.5 cm thick took 9 months to air dry. The wood is soft to moderately hard, and strong. At 12% moisture content, the modulus of rupture is about 110 N/mm², modulus of elasticity 15,100 N/mm² and compression parallel to grain 50 N/mm².
The wood is easy to saw and work, especially when green. It finishes fairly well and takes a high polish. It can be peeled into good-quality veneer that can be glued well to make good plywood. It is generally rated as non-durable, but samples from Rwanda and Indonesia have been rated moderately durable. Impregnation of the sapwood is easy, but that of the heartwood is erratic. The sapwood is highly susceptible to fungal and insect attacks.
The seed oil was found to contain 84% of lupeol.
Botany
Evergreen or deciduous, medium-sized tree up to 30(–50) m tall; bole columnar, branchless for up to 20(–30) m, up to 100(–250) cm in diameter, often with small buttresses; bark surface smooth or slightly rough, pale grey or pale brown; twigs often with prominent lenticels. Leaves arranged spirally, bipinnately compound with (2–)3–5 pairs of pinnae and 4–7(–9) pairs of leaflets per pinna, with or without a terminal leaflet; stipules small, caducous; petiole and main rachis up to 80 cm long; leaflets ovate to ovate-oblong, 3.5–18 cm × 1.5–8.5 cm, slightly wavy, acuminate at apex. Inflorescence an axillary raceme up to 30 cm long. Flowers bisexual, regular, 5-merous; pedicel 4–10 mm long; calyx with ovate or triangular lobes 2.5–4 mm long, short-hairy outside; petals free, oblong, 5–9 mm long, dark red, short-hairy; stamens alternating with petals, 15–18 mm long; ovary superior, oblong to linear, 12–15 mm long, stiped, hairy, style incurved. Fruit an elongate, flattened pod 8–17 cm long, distinctly stiped, narrowly winged, dehiscent with 2 valves, up to 18-seeded. Seeds lens-shaped, c. 6.5 mm × 5 mm, smooth, brownish. Seedling with epigeal germination; hypocotyl elongated; cotyledons leafy, slightly fleshy.
Early growth is very rapid. In nurseries in Rwanda seedlings were on average 40 cm tall after 3 months, but in Madagascar it was recorded that they need some time to develop a root system before growth of the stem starts. In India seedlings were 1 m tall after 5.5 months. In Malawi a mean annual increment of 2-year-old plants of 2.7–3.3 m in height and 6–7 cm in diameter was reported. Growth of older trees is still rapid, as observed in Tanzania where the mean annual increment of 13-year-old trees was 1.2 m in height and 1.9 cm in diameter. In Rwanda the mean height of trees was 1.5 m after 1 year, 4.4 m after 2 years, 6.7 m after 3 years, and 19 m after 24 years with a bole diameter 35 cm.
Young leaves are characteristically bright red. The trees flower after shedding their leaves. Apparently, Acrocarpus fraxinifolius does not have nitrogen-fixing root nodules.
Acrocarpus comprises a single species. In molecular studies it was found to be most closely related to Ceratonia.
Ecology
Acrocarpus fraxinifolius grows best in submontane areas in the more humid tropics with a short dry spell. In western Indonesia it occurs on fertile and constantly wet soils in the forest, at 600–1200 m altitude. In India and Myanmar it occurs in regions with an annual precipitation of over 2000 mm, growing best in deep, well-drained, clay-loam soils with a pH of 4–7. In Kenya, Uganda and Tanzania it performs best at moderate altitudes (1000–1500 m), on red soils and with a moist climate. In Rwanda Acrocarpus fraxinifolius is planted up to 1700 m altitude, in DR Congo up to 2100 m. It prefers mean annual temperatures of 19–28°C. It is sensitive to drought and frost.
Management
Under natural conditions Acrocarpus fraxinifolius regenerates primarily in small, burnt areas, on open patches where fresh soil has been exposed and along newly constructed roads. It is a light demander and pioneer, but can tolerate slight shade when young.
There are 13,000–47,000 dry seeds per kg. Collected seed should be left to air dry for about 10 days and can then be stored for many years in airtight containers when kept cool. However, a germination rate of only 30% after 5 years of storage has been reported. Seed should be pre-treated with sulphuric acid for 10 minutes or by hot water (80°C) for 15 minutes and left to imbibe in water for 12–24 hours before it is sown in the shade. A germination rate of 80–95% within only 2–7 days is achieved after those pre-treatments. Under natural conditions some seeds may germinate within a week, while others may lie dormant for one year before germinating. The seedlings are pricked out into beds or containers and placed in full sunlight. Seedlings are ready for planting when 3 months old and 30–45 cm tall. Seedlings from the nursery beds can be planted bare-rooted or as stumps or striplings. The use of wildlings is reported for India. Patch budding gave 80% success when establishing seed orchards.
Periodic weeding is required and the first thinning must be performed 3–4 years after planting. As the trees require a large crown for optimal growth, regular thinnings are necessary until the stand is fully developed. The tree coppices vigorously, in Rwanda some sprouts reaching 5 m after 2 years, but in Malawi poor coppicing ability has been noted. In agroforestry systems on favourable sites a mean annual increment of 10 m³/ha may be expected. In Burundi the wood volume was 6.7 m³/ha 3.5 years after planting in a spacing of 4 m × 8 m and intercropped with banana and bean. In Malawi 2-year-old trees yielded 33 t/ha of total above-ground biomass. In East Africa the rotation period for fuelwood production is 8–10 years, for timber production 30–40 years.
Young trees are susceptible to termite attack. In India serious defoliation of seedlings in nurseries and young plantations by grasshoppers and caterpillars has been reported. In nurseries in Mexico, damping-off has been recorded as a major disease. On humid soils Acrocarpus fraxinifolius is reported to be susceptible to Armillaria mellea. When rainfall is insufficient (less than 1500 mm/year) and a pronounced dry season occurs, the fast early growth may be followed by stagnation and high mortality.
Genetic resources and breeding
A germplasm bank and a seed orchard had been established by 1986 in Arunachal Pradesh in India. India and Kenya are the major seed-exporting countries.
Prospects
Acrocarpus fraxinifolius is a good candidate for timber plantations in slightly higher-altitude and more humid regions in Africa. It is easy to raise in the nursery, its survival after planting is generally very high and it grows fast. It usually develops a single and clear bole, making it suitable for pole production and fuelwood production under short rotation and with the possibility of coppice regeneration. It seems possible to establish commercial timber plantations with this species with a rotation period of 30 years.
Major references
• Blaser, J., Rajoelison, G., Tsiza, G., Rajemison, M., Rabevohitra, R., Randrianjafy, H., Razafindrianilana, N., Rakotovao, G. & Comtet, S., 1993. Choix des essences pour la sylviculture à Madagascar. Akon’ny Ala: Bulletin du Département des Eaux et Forêts 12–13. 166 pp.
• Boer, E. & Lemmens, R.H.M.J., 1998. Acrocarpus Wight ex Arn. In: Sosef, M.S.M., Hong, L.T. & Prawirohatmodjo, S. (Editors). Plant Resources of South-East Asia No 5(3). Timber trees: Lesser-known timbers. Backhuys Publishers, Leiden, Netherlands. pp. 41–43.
• Chikamai, B.N., Githiomi, J.K., Gachathi, F.N. & Njenga, M.G., undated. Commercial timber resources of Kenya. Kenya Forestry Research Institute (KEFRI), Nairobi, Kenya. 164 pp.
• Katende, A.B., Birnie, A. & Tengnäs, B., 1995. Useful trees and shrubs for Uganda: identification, propagation and management for agricultural and pastoral communities. Technical Handbook 10. Regional Soil Conservation Unit, Nairobi, Kenya. 710 pp.
• World Agroforestry Centre, undated. Agroforestree Database. [Internet] World Agroforestry Centre (ICRAF), Nairobi, Kenya. http://www.worldagroforestry.org/ resources/databases/ agroforestree. Accessed January 2009.
Other references
• CAB International, 2005. Forestry Compendium. Acrocarpus fraxinifolius. [Internet] http://www.cabicompendium.org/ fc/datasheet.asp?CCODE= ACR_FR. Accessed February 2009.
• Ding Hou, Larsen, K. & Larsen, S.S., 1996. Caesalpiniaceae (Leguminosae - Caesalpinioideae). Flora Malesiana. Ser. 1 - Spermatophyta. Vol. 12. Foundation Flora Malesiana, Rijksherbarium/Hortus Botanicus, Leiden University, Leiden, Netherlands. pp. 409–730.
• Maghembe, J.A. & Prins, H., 1994. Performance of multipurpose trees for agroforestry two years after planting at Makoka, Malawi. Forest Ecology and Management 64: 171–182.
• Mbuya, L.P., Msanga, H.P., Ruffo, C.K., Birnie, A. & Tengnäs, B., 1994. Useful trees and shrubs for Tanzania: identification, propagation and management for agricultural and pastoral communities. Technical Handbook 6. Regional Soil Conservation Unit/SIDA, Nairobi, Kenya. 542 pp.
• Moller, K., 1990. Note technique sur le comportement initial de quatre espèces d’arbres vulgarisées par le PARV dans son action agroforestière. Akon’ny Ala 6: 14–27.
• Odermatt, O. & Sorg, J.-P., 1981. Acrocarpus fraxinifolius Wight à l’arboretum de Ruhandé Butaré (Rwanda). ISAR, Rwanda. 32 pp.
Sources of illustration
• Boer, E. & Lemmens, R.H.M.J., 1998. Acrocarpus Wight ex Arn. In: Sosef, M.S.M., Hong, L.T. & Prawirohatmodjo, S. (Editors). Plant Resources of South-East Asia No 5(3). Timber trees: Lesser-known timbers. Backhuys Publishers, Leiden, Netherlands. pp. 41–43.
Author(s)
R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
Based on PROSEA 5(3): ‘Timber trees: Lesser-known timbers’.

Editors
R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
D. Louppe
CIRAD, Département Environnements et Sociétés, Cirad es-dir, Campus international de Baillarguet, TA C-DIR / B (Bât. C, Bur. 113), 34398 Montpellier Cedex 5, France
A.A. Oteng-Amoako
Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana
Associate editors
E.A. Obeng
Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana
Photo editor
G.H. Schmelzer
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article:
Lemmens, R.H.M.J., 2010. Acrocarpus fraxinifolius Arn. In: Lemmens, R.H.M.J., Louppe, D. & Oteng-Amoako, A.A. (Editors). Prota 7(2): Timbers/Bois d’œuvre 2. [CD-Rom]. PROTA, Wageningen, Netherlands.
1, tree habit; 2, leaf; 3, inflorescence; 4, flower; 5, fruit.
SourceEnglish




obtained from Zimbabweflora



wood in transverse section


wood in tangential section


wood in radial section